Electromagnetic device.



G. W. ELMEN. ELECTROMAGNETIC DEVICE.

APPLICATION FILED OCT-.10. 1911.

Patented Apr. 22, 1919.

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Q 0 WA fiagnef/z/ny Curran //7 V/7f0/.' r Gusfaf W. 5 /men UNITED STATES PATENT OFFICE.

GUSTAI W. ELMEN, OF BOGOTA, NEW JERSEY, ASSIGNOB TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTROMAGNETIC DEVICE.

Specification of Letters Patent.

Patented Apr. 22, 1919,.

Application filed October 10, 1917. Serial No. 195,728.

To all whom it may concern:

Be it known that I, GUSTAF W. ELMEN, formerly a subject of the King of Sweden, but now a citizen of no country in view of the fact that I have not registered with the Swedish consul, as required b the laws of Sweden, and now residing at o ota, in the county of Bergen and State of ew Jersey, have invented certain new and useful Improvements in Electroma etic Devices, of which the following is a ull, clear, concise, and exact description.

This invention relates to electromagnetic devices, and more particularly to electromagnetic circuit controlling devices or relays having retractible armatures.

This invention is a modification and improvement of the electromagnetic device covered by an application of James A. Wotton, Serial No. 188,824 filed August 29, 1917, and assigned to the same assignee as the present application. The general object of this invention is to provide an electroma netic device or relay which, while more e cient-in operation, still is of simple construction. 7

Generally speaking, an electromagnetically-operated device embodying this invention is characterized by the provision of means whereby the actuating flux path may be subjected to auxiliary longitudinal magnetization for the purpose of causing the armature to release at a higher value of actuating magnetization of the core and, consequently, for the purpose of decreasing the difference between the actuating and releasing current values of the device. More specifically considered, the invention is characterized b the rovision of means whereby the core 0 an e ectromagnetically-operated device may be subjected to auxiliary magnetization'by means of alternating current flowing through an auxiliary winding on thelore or through the actuating winding itse This. invention will be more clearly understood by reference to the drawings, in which Figure 1 is a schematic representation of an electromagnetic device or relay embodying an auxilia ma etizing winding in accordance with tllls invention; Fi 2 is a modified embodiment of the invention showing schematically the use of the actuating windin for accomplishin the auxiliary magnetization of the core; i .3 is a graphic representation showing the re ation between current in the energizing winding of the dewoes of either Fig. 1 or Fig. 2 and the flux produced thereby in the magnetizing circuit under both the ordinary operation conditrons and under the more exacting conditrons satisfied by this invention; and Fig. 4 shows graphically the relation between the current inthe magnetizing windings of the devices of Fig. 1 or'Fig. 2 and the pull on the armature produced thereby under condit10ns similar to those of Fig. 3.

In Fig. 1 of the drawings, an electromagnetic device or relay is shown having a core 5, an armature 6 and the return magnetic path 7. An energizin winding 8 may be supplied with current roin a direct current or other source of energy 9 through a key 10. The armature 6 is normally held in retracted position against a back stop 11 by means of a retractile spring 12. This armature may be provided with a contact member 13 adapted to have contact with a spring 14 upon the actuation of the armature 6. The closure of contact members 13 and 14 causes the auxiliary magnetization of the core by allowing alternating current to flowv in an auxiliary winding 15 supplied by an alternating cur: rent generator 16.

In the modified embodiment of the invention shown in Fig. 2, an electromagnetic device similar to that of Fig. 1 is there shown. the auxiliary winding 15 being omitted. The armature 6 may be actuated by means of current flowing in the winding 8, supplied by the direct current generator or other source of energy 9, through the key 10 and a retardation coil 17. The actuation of the armature 6 also effects the engagement of contact members 13 and 14, thereby causing auxiliary magnetization of the core by means of alternating current flowing in the winding 8, supplied by the alternating current generator 16, through a condenser 18. The function of the retardation coil 17 is to prevent alternating current from flowing through the direct current generator 9, while that of the condenser 18 is to prevent direct current from flowing through the alternating current generator 16.

It is to be noted that contact members,

such as 13 and 14, need not necessarily be controlled by the actuation of the armature, but may be actuated in some other way whereby they can be brought into engagement before the actuation of switch 10 in either of the embodiments of Figs. 1 or 2.

The effect of an alternating current passing through a core upon the magnetic characteristics thereof will be more clearly understood by reference to Fig. 3. Graph A represents the magnetization curve obtained by passing successively increaslng values of current through the main winding 8 of the relay of Figs. 1 or 2 and measuring, the corresponding values of magnetic flux in the core. Graph 2 represents a snmlar magnetization curve obtained from the same core, while alternating current from the generator 16 is passing either through the auxiliary winding 15 of Fig. 1 or the mam winding 8 of Flg. 2. This characteristic behavior of magnetic material is discussed by ProfessorEwing in his book on the Magnetic Ind action in lronami Other M etale. The effect of the phenomenon represented by the magnetization curves of Fig. 3 is that a given current value a will nor mallyproduce a value of flux I), while a larger flux value, represented by 0, will result when alternating current is passing through the magnetic material of the core.

'Or viewing it from another angle, a smaller,

value of current d when alternating current is flowing will produce the same amount of flux b as is normally produced by a current value a.

Referring now to Fig. 4, curve C corresponds to the initial magnetization curve A of Fig. 3; D and E being successive branches of a curve similar to the well known magnetization loop obtained by cyclic magnetization of magnetic material. Curve F corresponds to the magnetization curve B of Fig. 3, and also represents the two branches of the magnetization loop, which have become'merged into one, due tothe alternating current magnetization of the core. Only those parts of these curves which indicate the actual pull on the armature when the relay is in use are shown in full lines, the remaining portionsrepresented by the broken lines being shown merely for clearness of description.

First, let it be assumed that the engagement of contacts 13 and 14 is caused by means other than the actuation of the armature 6, and that the engagement has taken place before the closure of switch 10. Further, let it be assumed that a pull on the armature, represented by e of Fig. 4, is necessary to attract it from its retracted position; while a pull f is required to hold it in actuated position. Under ordinary conditions of operation, represented by curves C and D, a value of direct current- 72. would be required to actuate the armature; the maximum value obtained by the current, as detcrmincd by the voltage of the generator 9, being represented b r Upon opening the circuit at key 10, the current would fall and the armature would remain attracted until the current had reached the value a, whereupon the pull wouldbe reduced to the releasing value. f and the armature would fall back into retracted position. The corresponding current values required. when alternating current is passing through either the winding 15 of Fig. 1 or the main winding 8 of Fig. 2 are k, g and m.

It is, therefore, clear that, while the maximum energizing current, as determined by operating conditions, may be the same in either case, the armature will first be attracted by a substantially smaller value of energizing current when alternating current is flowing, and will be retracted, on the other hand, at a substantially higher value. The margin of operation, which, in either case, is determined by the ratio of releasing current. to operating current, will be substantially higher when the auxiliary magnetization, due to the alternating current, is effective; as shown by the ratio of m to In as compared with n to h.

a In the devices of Figs. 1 and 2, where the auxiliary magnetization of the core is not effective until the armature has been actuated upon the closure of switch 10, the effeet is not to change the value of current required to actuate the armature, such as h,- but to cause the armature to release at a higher value of actuating current, such as m. The effect even here of the alternating current is to substantially increase the ratio of releasing current to operating current, as shown by the ratio of m to It as compared with n to it; while simplicity of operation and increased efiiciency result from the automatic application of the auxiliary magnetizing alternating current. In these devices, 110 the actuation ot' the armature is substantially in accordance with curve C of Fig. 4, while the release of the arniature is substantially in accordance with curve F of the same figure.

There would be in practice a slight discontinuity in the curves of Fig. 4, at the point where the armature changes from its retracted position to its actuated position and vice versa, due to the consequent change 120 in reluctance of the magnetic circuit; but for the purpose of simplicity, such slight discontinuity has not been shown.

What is claimed is:

1. In an electromagnetieally-operated de- 125 vice, a core, an armature in operative relation thereto, an actuating winding, and means operative upon the actuation of said armature to cause alternating lengthwise magnetization of said core.

2. In an electromagnetically-operated device, a core, an armature in operative relation thereto, means comprising an energizing winding supplied with direct current for causing said core to attract said armature, and means comprising an auxiliary windinfg supplied with alternating current to acce erate, by alternating magnetization of said core, the release of said core in response to decrease in said direct current.

In witness whereof, I hereunto subscribe my name this 5th day of October A. D., 1917.

GUSTAF W. ELMEN. 

